Vibration detector

ABSTRACT

For use in detecting vibrations of rotary equipment or the like, the apparatus incorporating a case enclosing a rolamite structure including a pair of cylindrical rollers and tension band, the band being biased to position the rollers at a range of locations on normal or non-excessive vibrations wherein an increase in vibrations moves the cluster to an alternative position to thereby trigger operation of indicator equipment associated with the vibration detector.

United States Patent Harrah et al.

1 VIBRATION DETECTOR [72] Inventors: Robert S. Harrah, PO. Box 14410,Houston, Tex. 77021; Manmohan Suigh Kalsi, 8706 Ambiewood Drive,Houston, Tex. 77072 [73] Assignee: said Hurrah, by said Kalsi [22]Filed: Oct. 27, 1969 [21] App1.No.: 869,718

[52] US. Cl. f. ..1l6/70, 73/492, 74/89.2 [51] Int. Cl. ..G01l19/12 [58]Field of Search] 16/] 14, 112, 70,114 AH, 124;

73/492; 74/89.20; ZOO/61.45, 52, 153

[56] References Cited UNITED STATES PATENTS 2,764,894 10/1956 Faxen..74/89.2 3,452,175 6/1969 Wilkes ..200/153 3,452,309 6/1969 Wilkes..200/52 X 3,512,498 5/1970 Luebkc ..116/114 51 Oct. 17, 1972 OTHERPUBLICATIONS Publication: Rolamite: A New Mechanical Design ConceptResearch Report S C- RR- 67- 656A, Pages 116,119, Dec. 1967, D. F.Wilkes, 1322 Sandia Laboratory, Albuquerque, NM.

Primary Examiner-Louis .l. Capozi Attorney-Donald Gunn [57] ABSTRACT Foruse in detecting vibrations of rotary equipment or the like, theapparatus incorporating a case enclosing a rolamite structure includinga pair of cylindrical rollers and tension band, the'band being biased toposition the rollers at a range of locations on normal or non-excessivevibrations wherein an increase in vibrations moves the cluster to 'analternative position to thereby trigger operation of indicator equipmentassociated with the vibrationdetector.

10 Claims, 4 Drawing Figures PATENTED B 17 I973, 3.6 98 351 FIG] A 3% B2/5 c f 0 I I I H y 1 L0 'I W I l fi Robert S. Hurrah Manmohan S. Ka/siINVENTORS F/G.2 BY 2 ATTORNEY VIBRATION DETECTOR SUMMARY OF PROBLEM ANDSOLUTION Rotary equipment is often subject to slow failure during whichtime the vibrations in the equipment increase steadily. At somejuncture, the vibrations are defined as excessive and the apparatusshould, by all rights, be shut down for repairs and prevention of damagearising from continued operation of the gear. Vibration detectiondevices have been known in the past, but have been generally foundwanting in that they are quite complex, and expensive to manufacture. Itis with these problems in view that the device of the present inventionis summarized as providing a rolamite assembly within a suitable casehaving suitable bias means acting on the rolamite cluster to maintain anequilibrium position during ordinary vibrations, and which forms andindication when the rolamite cluster is substantially translated fromits equilibrium position in response to vibrations. In the preferredembodiment, gas under pressure is delivered to the interior of thechamber and is blocked so long as the rolamite cluster is at itsequilibrium position. However, on excessive vibrations, movement of therolamite cluster lifts the tension ban from an exhaust port to therebybleed the pressure from the chamber and to provide a pneumatic signal tocooperative apparatus of any nature. A reset means is incorporated toreturn the rolamite clusterto its equilibrium condition for further useof the device.

Many objects and advantages of the present invention will become morereadily apparent from a consideration of the included specification anddrawings, wherein:

FIG. I is a sectional view of thevibration detector of the presentinvention in its equilibrium condition;

FIG. 2 is a sectional view taken along the line 2-2 of FIG. 1 showingthe set screw cooperative with the tension band which adjust thesensitivity of the apparatus FIG. 3 is a view of the tension band of thepresent invention; and,

' FIG. 4 is a force diagram indicating the lateral forces acting on therolamite cluster.

In the drawings, attention is first directed to FIG. 1 which illustratesthe vibration detector of the present invention. The vibration detector10 is formed in a closed housing which includes the upper wall 12, thelower wall 14. the right-hand end 16, and the lefthand portion 18. Incross-section, it will be appreciated that the apparatus is essentiallyrectangular. Within the case or housing is a rolamite cluster which isindicated generally by the numeral 20. The rolamite apparatus assumes anequilibrium position as shown in FIG. 1 to block the flow of pressurefluid from the inlet at 22 to the outlet at 24. When the vibrationbecomes excessive, the cluster is accelerated sufficiently to move thecluster to a position on the band at which the band exerts forces oflarge magnatude to further displace the cluster to the tripped position.In this position, a flow path is established between the outlets 22 and24 to thereby vent or reduce the pressure within the device 10. Since anopening to atmosphere provides an alarm signal to pneumatically operatedequipment that the apparatus should be shut down, through the use ofcooperative equipment, such a result in readily achieved. It will benoted from the foregoing that the vibration detector of the presentinvention provides the alarm signal to the equipment.

Considering the invention more in detail, the upper wall 12 and thelower wall 14 cooperate with the side walls to form a rectangularpassage way between the end caps or pieces 16 and 18. The rolamitecluster 20 received within the chamber includes a flexible band 26 whichpasses about the two rollers 28 and 30 in the manner illustrated. Theright-hand end of the band is fixed in position by a single bolt 32 orother suitable means. Likewise, the left-hand end of the flexible band26 is fixed in position by the similar bolt 34. It will be noted thatthe left-hand end of the flexible band terminates at the upper side wall12 whereas the righthand end of the band, as viewed in the drawings,terminates on the lower wall 14. Consequently, the movement of tworollers captured in loops of the band displaces the band from one wallto the other, which is accomplished through rolling contact and withoutfrictional slippage.

Note should be taken that the rollers 28 and 30 are captured inthe loopssuch that both rollers must roll and not slip. In operation, therolamite cluster travels to and fro along the length of the band, whenunimpeded, wherein the contact between the band and the side walls 12and 14 is a rolling removal of the band from the side wall. Moreover, asa particular point on the band becomes engaged by first one roller andthen the other, the engagement is strictly by rolling contact to therebyeliminate friction in operation of device. The rolamite cluster,including the central portions of the band 26 and the two rollers 28 and30, is urged to a central, equilibrium condition is achieved illustratedin FIG. 1. The equilibrium conditions is achieved in the followingmanner. As shown in FIG. 3, the flexible band 26 has a cut-out portionwith tab 36. The tab 36 projects over a set screw 38 which protrudesinto the chamber and passes through the cutout opening of the flexibleban 26 to slightly bend or deflect the tab 36. As shown in FIG. 1, therolamite cluster cannot roll to the left over the set screw 38. The setscrew displaces the tab 36 which creates the force which acts on therolamite cluster urging it to the right of FIG. 1. The extent to whichthe screw protrudes into the chamber determines the magnatude of thisforce. Thus, if the screw were completely withdrawn, the forcedisplacing the tab and urging the rolamite cluster to the right will bereduced to the minimum. More will be noted concerning the magnatude ofthis force when FIG. 4 is discussed hereinafter.

The tendency of the band 26 59 straighten out creates forces acting tothe left and to the right of the apparatus shown in FIG. 1. However,such forces are unequal because of the action the cut-out 85 whichweakens the tendency of that portion of the band to straighten out. Theresult of the cut-out 85 is to produce an unabalanced force tending tomove the cluster to the left. This force is opposed by the adjustableforce generated by the tab 36. The rolamite cluster 20 thus seeks anequilibrium as shown in FIG. 1 wherein a minimal force is maintained onthe cluster tending to move it to the left. On the other hand, thecurvature of the tension band 26 around the roller 30 and the force ofthe tab 36 provide a force tending to move the cluster to the right,and. thus equilibrium is achieved.

As shown in FIG. 3, the tension band 26 is flexed at point B whichgenerates a force tending to move the rolamite cluster to the right. Thepoint C corresponds with the first point of curvature between the roller28 and the side wall 14 and the flexible band 26 likewise generates aforce tending to move the rolamite cluster to the left. The band, so tospeak, tends to straighten out, and hence, serves as a spring generatingthe forces above described. Because of the presence of the cutout 85 theforces generated at point B in the band 26 are less than the forcesgenerated at point C. This tends to urge the rolamite cluster to theleft. As shown in the graph of FIG. 4, the positive forces are thoseforces which tend to move the cluster to the right, and the negativeforces tend to move the cluster to the left.

When the screw 38 is withdrawn, the cluster has a tendency to move tothe left. When the set screw 38 is extended as shown in FIG. 1, the tab36 is deflected and additional forces tending to move the cluster to theright are created. This is best shown in FIG. 4 wherein that portion ofthe curve indicated at 40 is subject to variation over a wide rangedepending on the amount of extension of the set screw 38. Once thecluster tends to break away from the effect of the set screw 38 andmoves somewhat to the right, it travels fully to the right-hand end toengage the reset mechanism because of the reduced forces created by thecut-out 44 shown in FIG. 3. The cut-out 44 is physically located to theright of the port 24. Once the cluster exposes the port 24 to thechamber within the housing, the point of bending between the roller 28and the side wall 14 coincides with the cut-out strip 44 and the band26, being weakened at this point, tends to move the entire cluster tothe right-hand extremity of movement as viewed in FIG. 1. When thecut-out portion 44 contacts the roller 28, a trip point is defined atwhich the cluster moves to the right, or the position tripped.

In summation, the foregoing describes how the rolamite cluster 20 iskept in equilibrium near to an unstable position with its sensitivitybeing adjusted by the position of the set screw 38, and yet how thecluster, when sufficiently vibrated, breaks free of the equilibriumposition and moves to the right. This movement will now be related tothe vibration indicator of the present invention and the manner in whichan alarm is formed will be further described.

The vibration indicator of the present invention is preferably used witha pneumatic system. The port 22 communicates with a suitable source ofpressure while the port 24 is a vent port. When the rolamite clustermoves to the right, the port 24 is exposed to atmosphere and pressuredrops in the line communicated with the port 22. This drop in pressureprovides the necessary pneumatic signal for cooperative apparatus,thereby completing the indication that the vibrations have becomeexcessive for the present apparatus.

The structure of the vibration indicator further includes a reset port48. The port 48 is connected through a passage 50 in communication witha cylindrical chamber 52. A push rod 54 extends through the chamber 52and carries a piston 56 which is sealed in the camber 52 by means of aconventional O-ring seal. The piston supports a plunger 58 whichprotrudes into the chamber and is adapted to contact the rolamitecluster 20 for moving it to the left.

As shown in FIG. I, the piston is located at its lefthand extremity ofmovement. This extremity of movement is determined by the position ofthe lock nut 62 carried on the plunger or push rod 54. The resetmechanism presently being described can be operated in either of twoways. The reset port 48 may be connected with a suitable source ofpressure, and on increase of pressure into the chamber 52, the piston 56is moved to the left and the rod 58 contacts the rolamite cluster andmoves it to the left, returning it to the equilibrium position. In thealternative, the exposed push rod 54 and lock nut 62 may be grasped byhand and moved to the left as viewed in the drawings to reset therolamite cluster. The reset plunger is forced back to the extreme rightor withdrawn position as soon as airsupply to port 22 is turned on, thusleaving the cluster at its equilibrium position without the plungerinterfering with movement of the cluster.

The indicator 10 is preferably assembled of several pieces, although theform or manner of fabrication and assembly is subject to a wide range ofvariation. In the preferred embodiment, major blocks are indicated atand 72 and are joined together by a number of stud bolts 74 extendingthrough the two blocks 70 and 72. The internal chamber is sealed againstleakage by an encircling 0-ring 78 which is clamped in position by theend plate 80 which is abutted against the body member 72. Moreover, theset screw 38 incorporates an O-ring 82 to prevent leakage along thetapped opening forthe set screw. The friction of the 0-ring keeps thescrew 38 from working loose due to vibration. In addition, the exhaustport 24 includes an O-ring at 84 which abuts against the lower or netherside of the flexible band 26 to seal the chamber provided for therolamite cluster against leakage. Other suitable 0-rings are carried onthe plunger 54 and the piston 56. By and large, the chamber within thehousing 10 is sealed against leakage.

In operation, the device of the present invention is installed with itslongitudinal axis (the axis parallel to the plunger 58) parallel to theaxis of vibration to be detected. If desired, the device of the presentinvention may be duplicated along orthagonal axes dependent on the modeof vibration expected for the equipment to be protected. The protectiveindicating device of the present invention is then connected at the port22 with a shut-off device or the like which is operated by a loss ofpressure. The port 24 provides a pressure vent to atmosphere, and may beequipped with a suitable connective line or may be left open as desired.The reset port 48 is connected with a reset line should this feature beused.

The device of the present invention is then observed during conventionaloperation of the equipment to be protected. Thus, if a large stationaryengine is to be protected by the indicating device 10, the setting ofthe screw 38 is adjusted until the rolamite cluster assumes the positionof FIG. 1. The screw is further extended until the cluster is on theverge of tripping and moving to the right. At this juncture, the screwadjustment is backed off perhaps a fraction of a turn to define a triplevel greater than the normal vibrations of the equipment but less thanvibrations which would be considered excessive. The device is then leftuntended and will continue to monitor vibration essentially withoutfailure or fatigue over an extended period of time.

At this juncture, operation of the device should be noted. A vent toatmosphere through the port 24 drops the pressure in the line connectedthrough the port 22 to form the pneumatic signal. It should be notedthat lifting the tension band 26 away from the mouth of the port 24opens the vent to atmosphere. The tension in the band26 is such that theport 24 is substantially sealed at signal levels.

, The present invention is particularly adapted to be installed indifferent environments having different magnatudes of vibration. In eachlocation,'the screw adjustment 38 is operated to offset the vibrationspresent and is then backed down to provide a desired margin between thesetting of the equipment and the trip level. Thus, the present devicemay be switched from an installation subject to small vibrations to aninstallation subject to substantial vibrations. The device is readilyinstalled and calibrated, without the use of precision instruments, inthe manner described above.

Many variations may be adapted in the present invention. It may behelpful to obtain an electrical indication of operation. In this case,an electrical contact is recessed in the wall 14. The tension band 26maintains contact with the electrical contact or terminal when thecluster is in the position shown in FIG. 1. However, movement of thecluster to the right ends the contact of the band 26 against theterminal to initiate a contact closure suitably adapted in forming anelectrical signal. This is readily easily obtained by connecting oneconductor to either end of the tension band 26 and another conductor tothe terminal. In some environments, electrical signals and apparatus arenot considered safe, and the device may be installed as a pneumaticindicator as described above.

Many adaptations and variations of the device are readily apparent toone skilled in the art. However, the scope of the present invention isdetermined by the claims appended hereto.

What is claimed is:

1. An indicating device comprising:

a. rolamite cluster means including a tension band and a pair ofrollers;

b. a case enclosing said rolamite cluster means, said case having a pairof opposing side walls, the distance therebetween being less than thesum of the diameters of said pair of rollers, and said tension bandbeing looped into a pair of bights to at least partially encircle saidrollers in the bights thereof wherein said rolamite cluster means has atleast a limited range of movement from a first position to a second anddifferent position;

c. bias means co-acting with said rolamite cluster means tending tomaintain said rolamite cluster means in the first position; d. saidrolamite cluster means having a mass requiring a force exceeding apredetermined level to move said rolamite cluster means from the firstto the second position;

e. alarm condition indicator means cooperatively arranged with respectto said rolamite cluster means to respond to movement of said rolamitecluster means from the first to the second position;

f. a piston and cylinder arrangement adapted to communicate withapressure fluid source; and,

.g. a plunger moved by said piston to contact said rolamite clustermeans to urge said rolamite cluster means to the first position from thesecond position.

2. The invention of claim 1 including a set screw acting against aportion of said tension band to create a variableforce acting on saidrolamite cluster means.

3. The invention of claim '1, wherein said tension band acts on saidrollers with a force tending to maintain said cluster means at the firstposition, there being a means for adjusting the force in a. range ofvalues.

4. The invention of claim 1 wherein said indicator means includes apressure inlet port in said case opening at a point covered by saidtension band when said rolamite cluster means is in the first positionbut exposed in said case on movement ofsaid rolamite cluster means tothe second position.

5. The invention of claim 4 wherein an outlet port is formed in saidcase and in communication with said inlet port selectly controlled bysaid tension band.

6. The invention of claim 5 wherein one side wall of said case has anopening means therein and a seal means surrounds said opening means andseals against said tension band, said inlet port being connectedthereto.

7. The invention of claim 1 wherein said cylinder is positioned withrespect to said case so as to direct said plunger toward said rolamitecluster means.

8. The invention of claim 7 wherein said case is formed of two separableportions, one incorporating said side walls and the other including saidcylinder.

9. The invention of claim 8 including a seal means between said twoportions for defining a leak-proof connection therebetween.

10. The invention of claim 1 further including a partially cut tab insaid tension band and wherein said tab is positioned adjacent one ofsaid side walls, and further including an adjustable protruding setscrew extending

1. An indicating device comprising: a. rolamite cluster means includinga tension band and a pair of rollers; b. a case enclosing said rolamitecluster means, said case having a pair of opposing side walls, thedistance therebetween being less than the sum of the diameters of saidpair of rollers, and said tension band being looped into a pair ofbights to at least partially encircle said rollers in the bights thereofwherein said rolamite cluster means has at least a limited range ofmovement from a first position to a second and different position; c.bias means co-acting with said rolamite cluster means tending tomaintain said rolamite cluster means in the first position; d. saidrolamite cluster means having a mass requiring a force exceeding apredetermined level to move said rolamite cluster means from the firstto the second position; e. alarm condition indicator means cooperativelyarranged with respect to said rolamite cluster means to respond tomovement of said rolamite cluster means from the first to the secondposition; f. a piston and cylinder arrangement adapted to communicatewith a pressure fluid source; and, g. a plunger moved by said piston tocontact said rolamite cluster means to urge said rolamite cluster meansto the first position from the second position.
 2. The invention ofclaim 1 including a set screw acting against a portion of said tensionband to create a variable force acting on said rolamite cluster means.3. The invention of claim 1, wherein said tension band acts on saidrollers with a force tending to maintain said cluster means at the firstposition, there being a means for adjusting the force in a range ofvalues.
 4. The invention of claim 1 wherein said indicator meansincludes a pressure inlet port in said case opening at a point coveredby said tension band when said rolamite cluster means is in the firstposition but exposed in said case on movement of said rolamite clustermeans to the second position.
 5. The invention of claim 4 wherein anoutlet port is formed in said case and in communication with said inletport selectly controlled by said tension band.
 6. The invention of claim5 wherein one side wall of said case has an opening means therein and aseal means surrounds said Opening means and seals against said tensionband, said inlet port being connected thereto.
 7. The invention of claim1 wherein said cylinder is positioned with respect to said case so as todirect said plunger toward said rolamite cluster means.
 8. The inventionof claim 7 wherein said case is formed of two separable portions, oneincorporating said side walls and the other including said cylinder. 9.The invention of claim 8 including a seal means between said twoportions for defining a leak-proof connection therebetween.
 10. Theinvention of claim 1 further including a partially cut tab in saidtension band and wherein said tab is positioned adjacent one of saidside walls, and further including an adjustable protruding set screwextending from said side wall and displacing said tab by a controlledand adjustable amount, said tab deflecting and forming a bias forceacting on said rolamite cluster means.